But perhaps the oddest items people pass through TSA screening
are the ones they've made to look threatening.

The TSA considers improvised explosive devices, or IEDs,
the "main threat" and one of the most important things that
officers have to find when screening passengers and
baggage.IEDs are particularly hard to find
because they could be made from some of the most common items,
even toilet paper.

"An IED is limited only by the imagination of the bomber and the
materials readily at hand," Bill Morgan, an explosives specialist
and TSA Academy instructor, told his class of new TSA recruits
when we visited the Federal Law Enforcement Training Center in
Glynco, Georgia, in July.

Historically, the TSA doesn't have the best track record for
catching threats. During a number of covert audits on passenger
and baggage-screening operations last year,
airport TSA screeners failed to detect banned weapons in 67
of 70 tests at dozens of airport checkpoints around the country,
prompting, among other things, a complete overhaul of
how new officers are trained.

And apparently a few passengers have decided to take it upon
themselves to keep the TSA on its toes.

"One of the weirdest things I've ever experienced on the
job is just people trying to package things in a way to see if we
can actually catch it," said Jason Pockett, a TSA
Academy instructor who joined the agency in 2010 as a TSO, during
Business Insider's visit to FLETC in July.

Pockett said he's seen all sorts of strange configurations, like
batteries taped to different types of Tupperware containers.

"When it comes through, it just doesn't look right. It's got an
unusual look to it," he said.

In 2015, the
TSA reports its officers screened more than 708 million
passengers, 1.6 billion carry-on bags, and 432 million checked
bags. So it's not all that surprising that TSOs are privy to some
fairly odd behavior.

Pockett said he's also seen some pretty gross — albeit
ingenious — attempts at dissuading TSOs from conducting
screenings. "We've had individuals put sensitive items like dirty
laundry in their bags just so we won't go in there," he said.